This invention is generally directed to a garage door opener and, in particular, to a garage door opener having a remote safety sensor that includes a dormant state and an active state.
Electronic garage door openers have taken many forms in the prior art. As these electronic garage door openers become more common and there are more instances of injury, rules with regard thereto have been proliferated by local, state and federal lawmakers. Effective as of Jan. 1, 1993 a rule has been placed into effect that all electronic garage doors installed must be equipped with a safety device that will reverse a closing door if an obstruction is present in the last six inches of the door's travel.
Garage door safety features have taken many forms since they were first developed. For example, one of the early features developed in the garage door industry was to include a type of pressure sensing device, such that, if the garage door were in the closing process, and a pressure was exerted in a direction opposite to closing, the garage door would reverse direction (open). This device was found to be not entirely adequate because once a force was exerted in the opposite direction, a sufficient pressure may have already been exerted against the object as to cause damage. For example, if a small child were in the path of the garage door, the child could be knocked down and injured prior to the garage door reversing direction.
A second type of safety system as shown in U.S. Pat. No. 4,922,168 (Waggamon et al.) includes infrared transmitters and receivers hard wired to the motor so that if an obstacle is located between the transmitter and receiver, which necessarily means in the path of the garage door the receiver would send a signal to a motor controller to reverse direction of the garage door. This device is sufficient for its provided purpose. However, it can be quite costly and time consuming to hardwire a transmitter and receiver device to a motor controller which is located away from the transmitter and receiver. For instance, the transmitter and receiver may be located at the bottom of the tracks near the ground, while the motor controller and motor are mounted at the opposite end of the track. This placement is necessitated by the purpose of each element; the detector must sense for obstructions near the ground and the motor must provide the appropriate lifting force to lift the garage door.
Not only is the cost of wiring the device time consuming and expensive, there is the additional problem that garage doors are essentially outdoor products that require high quality and costly electrical connectors due to their contact with the elements (rain, snow, cold weather, warm weather and general dampness) associated with a garage. Furthermore, since this is a safety feature, long term reliability is a requirement. Accordingly, a commercialized product must be designed so that it is not vulnerable to moisture and the connections between the sensors and the motor controller require expensive design and installation in order to meet industry water-soak and pressure requirements. Eliminating wiring altogether would thus provide significant economical advantages.
Wireless communication systems are not new; for example, a wireless system for detecting intrusions is shown in U.S. Pat. No. 3,967,258 (Bucy, Jr.). This system utilizes battery operated sensors that also incorporate a low battery sensor. This inclusion of the low battery sensor uses slightly more battery power than if the low battery sensor were not present. Accordingly, this does not help in providing increased battery life as is one of the goals of the present invention.
Accordingly, the present invention contemplates a wireless system that eliminates many of the problems associated with designing and installing hardwired garage door safety systems. However, the main problem with a wireless system (battery operated) is that wireless receivers use a substantial amount of energy. The battery life of such devices is relatively short if they are maintained in a continuously active state. To the extent that low-current receivers are available, they tend to be expensive and uneconomical for this application. Accordingly, the present invention overcomes the deficiencies in prior art hardwired system and overcomes the problems associated with a wireless system, namely limited battery life. This is accomplished by providing a low cost wireless remote system that includes a dormant state and an active state in order to minimize power consumption and maximize battery life.